1. Field of the Invention
The present invention relates to a zoom lens system and in particular to a zoom lens system suitable for a single-lens-reflex camera having an angle of view of 75 degrees or more in a wide-angle end state and a zoom ratio of 3 or more.
2. Related Background Art
A zoom lens system having a negative lens group locating at the most object side (a so-called negative-lead type zoom lens) is easy to be made a wide-angle lens and has been made various proposals. On the other hand, the negative-lead type zoom lens has a drawback that it is difficult to satisfy both of a high zoom ratio and a high speed. Accordingly, high-speed zoom lenses overcoming the drawback have been proposed such as Japanese Patent Application Laid-Open Nos. 2000-241704 and 2000-221399.
However, the zoom lenses proposed by the patent documents do not satisfy both of a wide angle of view in the wide-angle end state and a high zoom ratio.